The overall goal of this investigation is to examine the relationship of respiratory symptoms and illnesses, cigarette smoking, airways responsiveness, and markers of inflammation to growth and decline in lung function in two well-characterized and investigated community-based populations of children and adults. Data are available in two populations: the Childhood Respiratory Disease Study in East Boston (CRD) and the Normative Aging Study Population (NAS). This group has shown that increased airway responsiveness is associated with altered patterns of lung growth (in children) and reduced levels of lung function (in adults). They also have shown that airway responsiveness is cross-sectionally associated with chronic respiratory symptoms in both children and adults. However, asymptomatic airway responsiveness is extremely common, occurring in 20% to 60% of responsive subjects, depending on how responsiveness and chronic symptoms are defined. The clinical significance of asymptomatic bronchial responsiveness is unknown but potentially great. Asymptomatic bronchial responsiveness may represent subclinical or mild airway inflammation. Alternatively, it may represent differences in mechanical factors that lead to airway narrowing. The investigators propose to examine the epidemiologic, clinical, and biochemical correlates of airway responsiveness in asymptomatic and symptomatic subjects using a cohort design to address the hypothesis that individuals with asymptomatic increased airway responsiveness do not have the same risk for loss of lung function as those who are symptomatic. In addition, they propose to establish an epidemiologic core within Project 1 where they will utilize a nested case control design to examine broncoalveolar lavage (BAL) markers of inflammation in conjunction with their own and other projects.